From 79b4cc5ee7a8086ac2c9c0afa52e6d687ce1ffef Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Wed, 30 Jan 2008 13:32:50 +0100 Subject: debug: move WARN_ON() out of line A quick grep shows that there are currently 1145 instances of WARN_ON in the kernel. Currently, WARN_ON is pretty much entirely inlined, which makes it hard to enhance it without growing the size of the kernel (and getting Andrew unhappy). This patch build on top of Olof's patch that introduces __WARN, and places the slowpath out of line. It also uses Ingo's suggestion to not use __FUNCTION__ but to use kallsyms to do the lookup; this saves a ton of extra space since gcc doesn't need to store the function string twice now: 3936367 833603 624736 5394706 525112 vmlinux.before 3917508 833603 624736 5375847 520767 vmlinux-slowpath 15Kb savings... Signed-off-by: Arjan van de Ven CC: Andrew Morton CC: Olof Johansson Acked-by: Matt Meckall Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- kernel/panic.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index da4d6bac270..0ebea438278 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -20,6 +20,7 @@ #include #include #include +#include int panic_on_oops; int tainted; @@ -292,6 +293,20 @@ void oops_exit(void) (unsigned long long)oops_id); } +#ifdef WANT_WARN_ON_SLOWPATH +void warn_on_slowpath(const char *file, int line) +{ + char function[KSYM_SYMBOL_LEN]; + unsigned long caller = (unsigned long) __builtin_return_address(0); + + sprint_symbol(function, caller); + printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file, + line, function); + dump_stack(); +} +EXPORT_SYMBOL(warn_on_slowpath); +#endif + #ifdef CONFIG_CC_STACKPROTECTOR /* * Called when gcc's -fstack-protector feature is used, and -- cgit v1.2.3-70-g09d2 From 71c339116a216b181fc5e203ef51a033fe5e38cf Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Wed, 30 Jan 2008 13:32:50 +0100 Subject: debug: add the end-of-trace marker and the module list to Unlike oopses, WARN_ON() currently does't print the loaded modules list. This makes it harder to take action on certain bug reports. For example, recently there were a set of WARN_ON()s reported in the mac80211 stack, which were just signalling a driver bug. It takes then anther round trip to the bug reporter (if he responds at all) to find out which driver is at fault. Another issue is that, unlike oopses, WARN_ON() doesn't currently printk the helpful "cut here" line, nor the "end of trace" marker. Now that WARN_ON() is out of line, the size increase due to this is minimal and it's worth adding. Signed-off-by: Arjan van de Ven Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- kernel/panic.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 0ebea438278..d9e90cfe329 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -281,6 +281,13 @@ static int init_oops_id(void) } late_initcall(init_oops_id); +static void print_oops_end_marker(void) +{ + init_oops_id(); + printk(KERN_WARNING "---[ end trace %016llx ]---\n", + (unsigned long long)oops_id); +} + /* * Called when the architecture exits its oops handler, after printing * everything. @@ -288,9 +295,7 @@ late_initcall(init_oops_id); void oops_exit(void) { do_oops_enter_exit(); - init_oops_id(); - printk(KERN_WARNING "---[ end trace %016llx ]---\n", - (unsigned long long)oops_id); + print_oops_end_marker(); } #ifdef WANT_WARN_ON_SLOWPATH @@ -298,11 +303,14 @@ void warn_on_slowpath(const char *file, int line) { char function[KSYM_SYMBOL_LEN]; unsigned long caller = (unsigned long) __builtin_return_address(0); - sprint_symbol(function, caller); + + printk(KERN_WARNING "------------[ cut here ]------------\n"); printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file, line, function); + print_modules(); dump_stack(); + print_oops_end_marker(); } EXPORT_SYMBOL(warn_on_slowpath); #endif -- cgit v1.2.3-70-g09d2